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Wheat & Small Grains Timely Topics

Jointed Goatgrass Biotype Resistant to Beyond Discovered in Eastern Washington

The first case of jointed goatgrass resistant to imazamox, the active ingredient in Beyond herbicide, has been confirmed in Eastern Washington. A team of Washington State University scientists, led by Dr. Ian Burke, publicly announced their findings in the January 2017 issue of Wheat Life magazine.

Clearfield wheat varieties were first planted in Eastern Washington on a widespread basis beginning in the fall of 2003. The fact that it has taken 13 years to discover the first imazamox-resistant jointed goatgrass biotype is a bit of a surprise. Ian Burke said “If you had asked me back when I started working on this in 2006 when to expect to see resistance to Beyond in jointed goatgrass, I would have said ‘we should see it already!’”

The resistant biotype is 144 times more resistant than susceptible goatgrass plants. To see even a little response in the resistant plants, researchers had to use 6x the labeled use rate of Beyond. Jeannette Rodriguez, a WSU graduate student, is working to identify the mechanism of resistance. It is known that resistance in this instance was not the result of a cross between Clearfield wheat and jointed goatgrass.

Growers and fieldmen should scout jointed goatgrass patches in fields that they manage and submit samples that they have concerns about to the WSU Herbicide Resistance Testing Program. The Extension publication “Strategies to Minimize the Risk of Herbicide-resistant Jointed Goatgrass” provides information on the control of jointed goatgrass with an emphasis on prevention and management of herbicide resistance.

BASF issued the following statement in response to this discovery: “BASF is supporting WSU research aimed at preserving the long-term benefits of the Clearfield® Production System – with an emphasis on resistant jointed goatgrass. A multifaceted resistance management program is essential to preserve the long-term benefits of Beyond herbicide and the Clearfield Production System. Wheat producers are asked to help protect and prolong the usefulness of these technologies by following the specific recommendations and requirements highlighted in the Clearfield Stewardship Guidelines to help prevent the onset of herbicide resistance in weeds.”


For more information, contact Dr. Ian Burke at icburke@wsu.edu or 509-335-2858.

New Publication Addresses Acidic Soils and How They Interact with Root Diseases

As soil acidification continues to be a concern for growers in the Pacific Northwest, WSU researchers are working to provide information and recommendations for how to mitigate adverse effects. Root diseases are one of many factors influenced by acid soils, depending on the soilborne pathogen. The new publication, Acid Soils: How Do They Interact with Root Diseases?, explains how soil pH affects root diseases and also offers examples of common ones in the Pacific Northwest.

Cereal growers in the Pacific Northwest have been experiencing an increase in soil acidity (lower pH) primarily due to a long history of ammonium fertilizer use.

In eastern Washington and northern Idaho, soil acidification tends to be worse in areas that are annually cropped, do not include nitrogen-fixing legumes in the crop rotation, and in areas that were historically forested. Forested soils tend to have a lower pH buffering capacity, making them more prone to shifts in soil pH. These same areas also typically include more forage and seed grass production and seldom include legumes in rotation, meaning that there is more intensive nitrogen application to the soil.

In addition, direct seeding can result in a stratification of soil pH in which the top few inches of soil are more acidic. This is because acidification caused by fertilizer application in the top soil layers is not diluted by mixing with the more alkaline soil below the fertilizer zone. However, the contribution of this stratification on management of soil acidity in direct-seed systems has not been evaluated.


For questions or comments, contact Tim Paulitz at USDA-ARS Wheat Health, Genetics and Quality Research Unit (paulitz@wsu.edu or timothy.paulitz@ars.usda.gov) or Kurtis Schroeder, Assistant Professor in the Department of Plant, Soil, and Entomological Sciences at the University of Idaho (kscroeder@uidaho.edu).

FAQ: WSU Wheat and Barley Research and Royalties

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New Publication Compares Wheat and Canola Management

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Slime Mold on Wheat

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Winter Wheat Herbicide Efficacy Tables Helps Growers Narrow Herbicide Options

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Answers to Frequently Asked Questions About Falling Numbers

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